One process in golf ball production is the inspection of a golf ball's indicia (e.g., labels, logos, or other markings). After a golf ball is marked with such indicia, it is inspected to ensure that they are properly positioned on the golf ball's surface with minimal defect or blemish.
Various systems automate this process by using a camera that captures images of the indicia and a computer that compares the inspected images with one or more reference images of indicia on an exemplary golf ball, i.e., a golf ball that has no indicia defect or blemish.
A problem associated with this approach, however, is curvature distortion in the two-dimensional images of a three-dimensional curved golf ball. Because the indicia wrap around the ball according to its curvature, the further an indicium is from the point on the golf ball closest to the camera, the more distorted it appears. As the indicia are positioned away from the camera, they appear shortened and bunched together. When viewed by an area scan camera, the further an indicium departs from the center of the golf ball in any direction, the greater the curvature distortion. U.S. Pat. No. 6,462,812 discloses a system that uses an area scan camera to automatically inspect golf balls, but only after the system first orients the indicia directly in front of the camera, to account for curvature distortion in the golf ball inspection images.
U.S. Pat. No. 6,630,998 B1 discloses a golf ball inspection system that uses a line scan camera that requires preliminary orientating golf ball indicia directly in front of the camera, to account for curvature distortion. This commonly owned patent is incorporated herein by reference in its entirety. A line scan camera is a camera that captures a row of pixels. As a golf ball rotates, the line scan camera captures multiple such rows of pixels, which are then assembled to form a two-dimensional image of the golf ball's curved surface. This image captures the golf ball's indicia so that it can be automatically compared with a pre-selected reference or master image of an acceptable golf ball. A line scan camera does not eliminate curvature distortion on the scanned image.
To provide a meaningful basis for inspection, the systems disclosed in the '812 and '998 patents capture scanned images under conditions that are similar to the conditions under which the stored master image was obtained. As mentioned above, these systems orient inspected balls so that when scanned, the orientation of the scanned images should, as closely as possible, match orientation of the master image. It typically takes between 1.5 to 2 seconds to orient each ball. In addition, orienting inaccuracy also requires loosening of inspection standards. If a golf ball is not perfectly centered in front of a camera, application of stringent inspection standards could cause an acceptable golf ball to be rejected. Plus, accurately orienting a ball requires the added step of preliminarily detecting an indicium's original position before the golf ball can be oriented.
Hence, there remains a need for inspecting golf balls and other curved objects without orienting.